In a food processor, pulse the nuts until finely blended; add in the Parmesan cheese and pulse until incorporated with the nuts; top with the fresh basil and pulse some more

This will form a thick paste. It’s a good idea to scrape it down from the sides at this point before you add in the oil; with your food processor running on low, slowly add in a stream of good quality olive oil ~ about a 1/2 cup

Season with kosher salt & black pepper to taste; drizzle in a tablespoon or two of warm water just until the pesto is the desired consistency